One commonly available type of agricultural conveyor for conveying particulate materials uses an endless conveyor belt having an upper run extending longitudinally through a conveyor tube that is supported to extend at an upward slope from a pickup housing at an inlet end of the tube to a discharge spout at an outlet end of the tube. With use, the conveyor belt tends to stretch which reduces tension on the belt and results in slippage of the belt relative to drive rollers. To accommodate for the stretch, the belt path commonly passes around a tension roller which can be adjustably positioned relative to the frame for varying the overall length of the belt path. The tension roller is commonly supported using springs and threaded mounts. These springs result in an uneven belt tension throughout the range of extension of the springs, whereas the threaded mounts are typically quite limited in range. Each time the limited range of movement of the tension roller is exceeded by the stretch in the conveyor belt, a section of the conveyor belt must be cut out which results in time consuming and costly maintenance.
The endless conveyor belt is typically driven to rotate by connecting a motor to one of the rollers supporting the endless conveyor belt thereon. Typically, the drive transmission between the motor and the drive roller results in a quick and sudden acceleration of the drive roller from a static position to the operating speed resulting in slippage and wear of the endless conveyor belt relative to the driver roller upon each start up. This wear on the endless conveyor belt also shortens the lifespan of the endless conveyor belt.